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Upgrading and Repairing PCs, 16th Edition
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Upgrading and Repairing PCs, 16th Edition

4.6 3
by Scott Mueller

Editorial Reviews

The Barnes & Noble Review
If you've ever upgraded a PC, or fixed one, or if you plan to, you need Scott Mueller's legendary reference, Upgrading & Repairing PCs. As you'd expect, Mueller's new 16th edition is thoroughly updated to reflect the latest in everything from power supplies to eighth-generation video cards. As you might not expect, he's added a thorough introduction to overclocking and hardware hacking: how to squeeze max performance out of your PC, without frying it.

You'll find detailed coverage of the latest 64-bit processors, along with the new motherboards, memories, and chipsets that complement them. As part of Mueller's thorough chapter on optical storage, he demystifies the bewildering menagerie of DVD standards (DVD+RW, DVD-RAM, DVD-R, DVD-RW). And, as the value of computers increasingly moves to the network, he continues to deepen his networking coverage -- especially Wi-Fi.

Since most computers that need repair or upgrading aren't new, Mueller presents systematic coverage of mainstream technologies, including BIOSes, hard drives, audio hardware, I/O -- you name it. He discusses removable storage media ranging from today's external USB 2.0 and FireWire drives to those failed media formats that doubtless hold your Great American Novel. His detailed coverage of backup/restore includes guidance on recovering data that seems irretrievably lost (even data on formatted, repartitioned, or erased hard drives and formatted flash memory devices).

Last but definitely not least, there's a DVD with two full hours of up-to-date digital video, shot on a new professional set with expert lighting and camerawork. You'll see every last detail, whether you're viewing on a PC or your TV (hey, your computer could be open for surgery)! Bill Camarda

Bill Camarda is a consultant, writer, and web/multimedia content developer. His 15 books include Special Edition Using Word 2003 and Upgrading & Fixing Networks for Dummies, Second Edition.

Product Details

Publication date:
Edition description:
Book with DVD
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7.68(w) x 9.24(h) x 2.59(d)

Read an Excerpt

PC Components, Features, and System Design

System Types

PCs can be broken down into many categories. I like to break them down in twoways—by the type of software they can run and by the motherboard host bus,or processor bus design and width. Because this book concentrates mainly onhardware, let's look at that first.

When a processor reads data, the data moves into the processor via theprocessor's external data bus connection. The processor's data bus isdirectly connected to the processor host bus on the motherboard. The processordata bus or host bus is also sometimes referred to as the local busbecause it is local to the processor that is connected directly to it. Any otherdevices connected to the host bus essentially appear as if they are directlyconnected to the processor as well. If the processor has a 32-bit data bus, themotherboard must be wired to have a 32-bit processor host bus. This means thesystem can move 32 bits of data into or out of the processor in a singlecycle.

See "Data I/O Bus," p. 46.

Different processors have different data bus widths, and the motherboardsdesigned to accept them require a processor host bus with a matching width.Table 2.2 lists all the Intel and major Intel-compatible processors, their databus widths, and their internal register sizes.

Table 2.2  Intel and Intel-Compatible Processors and Their DataBus/Register Widths


Data Bus Width

Register Size






















Pentium Pro/Celeron/II/III



AMD Duron/Athlon/Athlon XP



Pentium 4






AMD Athlon 64



A common misconception arises in discussions of processorwidths. Although the Pentium and newer processors all have 64-bit data buswidths, their internal registers are only 32 bits wide, and they process 32-bitcommands and instructions. The Intel Itanium and AMD Athlon 64 are the firstIntel-compatible processors to have 64-bit internal registers. Thus, from asoftware point of view, all chips from the 386 to the Athlon/Duron andCeleron/Pentium 4 have 32-bit registers and execute 32-bit instructions. Fromthe electronic or physical perspective, these 32-bit, software-capableprocessors have been available in physical forms with 16-bit (386SX), 32-bit(386DX and 486), and 64-bit (Pentium and beyond) data bus widths. The data buswidth is the major factor in motherboard and memory system design because itdictates how many bits move in and out of the chip in one cycle.

See "Internal Registers (Internal Data Bus)," p. 48.

The Itanium processor has a new Intel architecture 64-bit (IA-64) instructionset, but it can also process the same 32-bit instructions as processors rangingfrom the 386 through the Pentium 4. The Athlon 64 has a new x86-compatible64-bit architecture but is designed to use 32-bit instructions written fornormal Intel or compatible x86 processors as efficiently as a normal Athlon XPor comparable processor would.

See "Processor Specifications," p. 41.

Referring to Table 2.2, you can see that all Pentium and newer systems have a64-bit processor bus. Pentium processors, whether they are the original Pentium,Pentium MMX, Pentium Pro, or even the Pentium II/III or 4, all have 64-bit databuses, as do comparable processors from AMD (K6 family, Athlon, Duron, AthlonXP, and Athlon 64).

As you can see from Table 2.2, systems can be broken down into the followinghardware categories:

  • 8-bit

  • 16-bit

  • 32-bit

  • 64-bit

What is interesting is that besides the bus width, the 16- through 64-bitsystems are remarkably similar in basic design and architecture. The older 8-bitsystems are very different, however. This gives us two basic system types, orclasses, of hardware:

  • 8-bit (PC/XT-class) systems

  • 16/32/64-bit (AT-class) systems

In this verbiage, PC stands for personal computer; XT stands for an extendedPC; and AT stands for an advanced-technology PC. The terms PC, XT,and AT, as they are used here, are taken from the original IBM systems ofthose names. The XT was a PC system that included a hard disk for storage inaddition to the floppy drives found in the basic PC system. These systems had an8-bit 8088 processor and an 8-bit Industry Standard Architecture (ISA) bus forsystem expansion. The bus is the name given to expansion slots in whichadditional plug-in circuit boards can be installed. The 8-bit designation comesfrom the fact that the ISA bus found in the PC/XT class systems can send andreceive only 8 bits of data in a single cycle. The data in an 8-bit bus is sentalong eight wires simultaneously, in parallel.

See "The ISA Bus," p. 350.

16-bit and greater systems are said to be AT-class, which indicates that theyfollow certain standards and that they follow the basic design first set forthin the original IBM AT system. AT is the designation IBM applied to systems thatfirst included more advanced 16-bit (and later, 32- and 64-bit) processors andexpansion slots. AT-class systems must have a processor that is compatible withIntel 286 or higher processors (including the 386, 486, Pentium, Pentium Pro,Pentium II, Pentium III, Pentium 4, and Pentium M processors), and they musthave a 16-bit or greater system bus. The system bus architecture is central tothe AT system design, along with the basic memory architecture, interruptrequest (IRQ), direct memory access (DMA), and I/O port address design. AllAT-class systems are similar in the way these resources are allocated and howthey function.

The first AT-class systems had a 16-bit version of the ISA bus, which is anextension of the original 8-bit ISA bus found in the PC/XT-class systems.Eventually, several expansion slot or bus designs were developed for AT-classsystems, including the following:

  • 16-bit ISA/AT bus

  • 16-bit PC Card (PCMCIA) bus

  • 16/32-bit Extended ISA (EISA) bus

  • 16/32-bit PS/2 Micro Channel Architecture (MCA) bus

  • 32-bit VESA Local (VL) bus

  • 32/64-bit Peripheral Component Interconnect (PCI) bus

  • 32-bit CardBus (PCMCIA) bus

  • PCI Express bus

  • ExpressCard bus

  • 32-bit Accelerated Graphics Port (AGP) bus

A system with any of these types of expansion slots is by definition anAT-class system, regardless of the actual Intel or Intel-compatible processorthat is used. AT-type systems with 386 or higher processors have specialcapabilities not found in the first generation of 286-based ATs. These distinctcapabilities are in the areas of memory addressing, memory management, andpossible 32- or 64-bit wide access to data. Most systems with 386DX or higherchips also have 32-bit bus architectures to take full advantage of the 32-bitdata transfer capabilities of the processor.

Until recently, PC systems continued to incorporate a 16-bit ISA slot forbackward-compatibility and lower-function adapters. However, in virtually allmotherboards today, ISA slots have been completely replaced by PCI slots alongwith an AGP slot (a specialized expansion slot design) available in most systems(except for a few entry-level models with integrated video) for high-performancegraphics. In addition, most portable systems use PC Card (PCMCIA) and CardBusslots in the portable unit and PCI slots in optional docking stations.

Chapter 4, "Motherboards and Buses," contains in-depth informationon these and other PC system buses, including technical information such aspinouts, performance specifications, and bus operation and theory.

Table 2.3 summarizes the primary differences between the older 8-bit (PC/XT)systems and modern AT systems. This information distinguishes between thesesystems and includes all IBM and compatible models.

Table 2.3  Differences Between PC/XT and AT Systems

System Attributes

(8-Bit) PC/XT Type

(16/32/64-Bit) AT Type

Supported processors

All x86 or x88

286 or higher

Processor modes


Real/Protected/Virtual Real

Software supported

16-bit only

16- or 32-bit

Bus slot width



Slot type

ISA only

ISA, EISA, MCA, PC Card, CardBus, ExpressCard, VL-Bus, PCI, PCI Express, andAGP

Hardware interrupts

8 (6 usable)

16 (11 usable)

DMA channels

4 (3 usable)

8 (7 usable)

Maximum RAM


16MB/4GB or more

Floppy controller speed


250/300/500/1,000 Kbps

Standard boot drive

360KB or 720KB


Keyboard interface



CMOS memory/clock

None standard


Serial-port UART


16450/16550A or greater

The easiest way to identify a PC/XT (8-bit) system is by the8-bit ISA expansion slots. No matter which processor or other features thesystem has, if all the slots are 8-bit ISA, the system is a PC/XT. AT (16-bitplus) systems can be similarly identified—they have 16-bit or greater slotsof any type. These can be ISA, EISA, MCA, PC Card (formerly PCMCIA), CardBus,VL-Bus, or PCI. Any system using the new high-speed serial buses such as PCIExpress or ExpressCard also qualifies as an AT-class system. Using thisinformation, you can properly categorize virtually any system as a PC/XT type oran AT type. No PC/XT type (8-bit) systems have been manufactured for many years.Unless you are in a computer museum, virtually every system you encounter todayis based on the AT-type design.

Meet the Author

Scott Mueller is the most trusted, authoritative hardware voice in the industry. In addition to teaching hardware repair to more than 10,000 computer professionals and enthusiasts, he has sold more than 2 million copies of Upgrading and Repairing PCs, making him a world-renowned hardware author and his book a classic. Scott has taught hardware repair to a host of agencies in the U.S. and foreign governments, and corporations in the United States, Canada, Australia and Europe. Scott also is a feature writer for Maximum PC, the industry leading PC hardware magazine.

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Upgrading and Repairing PCs, 16th Edition 4.7 out of 5 based on 0 ratings. 3 reviews.
Guest More than 1 year ago
I consider myself fairly PC-saavy, not an expert, but fairly saavy. I thought this book might provide a tidbit or two at most that might be interesting. But having received it, I have to say that it simply blows me away! This book hugely exceeds my expectations, and upon thumbing through it, I found that I could barely put it down! It explains in a thorough and easily understood way all of the technical detail that you need to know -- the same information that other 'user manuals' leave out. Very well written and documented, and all information is laid out very logically and in an interesting manner. This book reads so that a 'normal' person can read it, yet it still dives into all of the technical detail that you could ever want. Very comprehensive, and it's over 2' thick. Get this book and you will NOT be disappointed!
Guest More than 1 year ago
The size of this book is larger than the average computer book because it has ALOT of info. To keep it short, this book is for those who have some knowledge of what they are doing because to a newcomer, this book IS overwhelming. If you like visual steps then this book is not really for you because this book contains bland pictures. However, this book does come with a very instructional DVD. Highly recommended.
Guest More than 1 year ago
This book was the most fascinating and most educational computer hardware book i have ever read. Im only 19, but ive read about 50 computer hardware books, and this one put the iceing on the cake ladys & gents. If you know your stuff, this book will even impress you. This book is highly recommanded.